FRAME SYNCHRONIZATION METHOD Russian patent published in 2007 - IPC H04L7/08 

FIELD: electric and radio communications; frame synchronization receiving devices of digital message transmitting and intercepting systems.

SUBSTANCE: proposed method includes sequential search at single-bit shift, identification of concentrated sync groups in group digital stream, and formation of responses when identifying concentration sync groups on tested clock intervals, and measurement of time intervals between sequential moments of responses across concentrated sync group identifier in terms of clock intervals. Primary sample of N ≥ 3 time intervals is accumulated. Secondary samples of time intervals between moments of first, second, through (N + 1)^th reference responses, respectively, and arrival moments of all other primary-sample responses are calculated. Maximal common dividers of probable combinations of two or more time intervals are calculated and particular lines (spectrums) of distribution of maximal common dividers whose values exceed lower boundary of region of probable group signal cycle lengths are formed in the framework of secondary time interval samples. Integrated spectrum of maximal common divider values is formed by summing up all particular maximal common divider spectrums. Regular sequence of true integrated sync group responses is detected by fact of coincidence of maximal common dividers in integrated spectrum whose quantity exceeds desired threshold, and coincidence point abscissa of maximal common dividers is assumed as cycle length. True concentrated sync group responses are identified in primary implementation of stream by serial numbers of particular maximal common divider spectrums wherein we see multiple coincidences of maximal common dividers with found cycle length. Clock interval of group-signal next cycles commencement is predicted. Concentrated sync group responses appearing at predicted clock intervals are assumed as frame synchronization pulses. Decision on input in and output from frame synchronization mode is taken by composite "k/m-r" criterion.

EFFECT: enlarged functional capabilities due to affording frame synchronization in absence of a priori data on group-signal cycle length without impairing noise immunity.

1 cl, 9 dwg